Micro-Electro-Mechanical System (MEMS) is a recently developed interdisciplinary cutting-edge high-tech field. MEMS applies micro silicon mechanical processing technology developed on semiconductor technology, mainly uses silicon as material, and implements sensing and controlling external information by manufacturing suspended movable three-dimensional structures of micron dimension size on a silicon chip. MEMS acceleration sensor is a sensor based on such technology.
It is well known that a basic structure of a capacitive MEMS acceleration sensor is a capacitor consists of a mass and fixed electrodes. When a displacement of the mass is produced by the acceleration, an overlapping area or a distance between the electrodes of the capacitor is changed, in this case, a measurement of the acceleration can be implemented by measuring the capacitance change of the capacitor. As one of the MEMS acceleration sensors, an acceleration sensor formed by a parallel plate capacitor is widely used because of its simple processing, less influence by parasitic capacitance and edge effect, and low requirement of processing circuit.
However, recently, due to a relatively small change range of the parallel plate capacitor in such acceleration sensor, the sensitivity of the sensor is relatively low.